It is standard to package a plurality of containers in a carrier harness that has a plurality of loops engaged snugly around the upper ends of the containers, which have beads or lids that project somewhat so that the loops can get under them. Such harness carriers are described in U.S. Pat. Nos. 3,232,422, 3,733,100, 3,874,502, 4,018,331, 4,033,457, 4,109,787, 4,121,712, 4,219,117, 4,462,494, 4,586,742, 5,115,910, and RE29,873. They are applied to the containers by machines such as described in U.S. Pat. Nos. 3,857,422, 4,070,850, 4,817,361, 5,054,257, and 5,117,609.
The main disadvantage of these systems is that they leave the upper ends of the containers exposed. When, as is the usual case, the containers are so-called flip-top cans, this means that the surfaces that will be put into direct contact with the mouth of a person drinking directly from the can might well be fairly dirty. Even if a straw is used, it is certain that dirt on the flip top, which typically is depressed down into the container, will be introduced into the beverage in the can.
It has therefore been suggested in U.S. Pat. Nos. 3,601,253 and 3,601,439 to provide a thin plastic membrane adhered to the surface of the carrier harness. Such arrangements have met no commercial success because the machinery that mounts the harnesses on the containers invariably punctures the membrane, thereby spoiling the package. Other systems such as described in U.S. Pat. Nos. 3,727,752, 4,523,676, 4,606,484, and 5,154,289 provide fairly good sanitary coverage, but use coverings that bear no resemblance to the known carrier harnesses so that the packager must refit with new machinery to use them. In the systems of U.S. Pat. Nos. 4,974,726, 5,099,632, and 5,184,448 a thick plastic sheet replaces the carrier harness and provides a reasonable amount of protection for the containers, but this sheet can only be applied by specialized equipment, and the protection is not complete so that some parts of the container rims are left exposed.
In U.S. Pat. No. 4,724,655 a solution is proposed where a thin plastic film is bonded to the edges of the harness but slack is left in the film so as to form pockets. In theory these pockets allow the installing fingers of the mounting machine to engage into the harness holes and stretch them over the container tops, but in reality these fingers are likely to poke holes through the film. Furthermore bonding the film to the carrier-harness strip is a fairly tricky job that increases the cost of the packaging somewhat.